Vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's thermodynamic tendency to evaporate. It relates to the balance of particles escaping from the liquid (or solid) in equilibrium with those in a coexisting vapor phase. A substance with a high vapor pressure at normal temperatures is often referred to as volatile. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the attractive interactions between liquid molecules become less significant in comparison to the entropy of those molecules in the gas phase, increasing the vapor pressure. Thus, liquids with strong intermolecular interactions are likely to have smaller vapor pressures, with the reverse true for weaker interactions.

蒸汽壓力是指在封閉系統中，在給定溫度下，蒸汽與其冷凝相（固體或液體）處于熱力學平衡時所施加的壓力。平衡蒸汽壓是液體蒸發的熱力學趨勢的指示。它涉及從液體（或固體）中逸出的顆粒與共存氣相中的顆粒的平衡。在常溫下具有高蒸氣壓的物質通常被稱為揮發性物質。存在于液體表面上方的蒸汽所表現出的壓力稱為蒸汽壓力。隨著液體溫度的升高，與氣相中那些分子的熵相比，液體分子之間的吸引相互作用變得不那么顯著，從而增加了蒸汽壓。因此，具有較強分子間相互作用的液體可能具有較小的蒸氣壓，較弱的相互作用則相反。

source URL: https://en.wikipedia.org/wiki/Vapor_pressure